Lead free reduced ricochet limited penetration projectile

ABSTRACT

A frangible projectile with a specific gravity similar to a lead projectile. The projectile comprises 34-94%, by weight, binder. The binder comprises poly ether block amide resin. The projectile further comprises 6-66%, by weight, ballast. The ballast comprises at least one member selected from a group consisting of tungsten, tungsten carbide, molybdenum, tantalum, ferro-tungsten, copper, bismuth, iron, steel, brass, aluminium bronze, beryllium copper, tin, aluminium, titanium, zinc, nickel silver alloy, cupronickel and nickel. The projectile can be prepared with a particularly preferred specific gravity of 5-14 and more preferably 11-11.5.

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION

[0001] The present invention relates to an improved compositeprojectile/projectile core with superior characteristics. Morespecifically, the present invention relates to a compositeprojectile/projectile core with a binder and a ballast, such as a metalor metal alloy, encased therein wherein the projectile is capable ofbeing manufactured at a specific gravity closely resembling lead metal.

[0002] There has been a long felt desire to reduce the amount of lead inthe environment. The impact of high levels of lead has been welldocumented and the desire to lower these levels is now well accepted.

[0003] The use of lead in projectiles, such as bullets or bullet cores,has been a widely accepted practice for generations. The intrinsicproperties of lead make it particularly suitable for use as aprojectile. Lead can be easily cast into desired shapes. The specificgravity and rheological properties of lead are particularly suitable foruse as a projectile. The weight is sufficient for accurate flight andthe material is soft enough to mushroom, or flatten into a disk, uponimpact. These properties combined provide optimal flight characteristicsand maximum kinetic energy transfer for effectiveness on impact. Thereis no suitable substitute for lead projectiles for hunting activities.The amount of lead entering the environment through hunting activitiesis minimal. Other metals may provide adequate specific gravities yet theability to mushroom is compromised and therefore the projectile may passthrough the intended target without mushrooming. This is undesirable asrealized in the art.

[0004] Hunting enthusiast typically desire to practice the art byshooting at targets to insure that sights are properly aligned. Thisdesire is in direct conflict with the desire to minimize lead depositionin the environment. If alternate projectiles are used the ballistics aredifferent from lead projectiles. This difference is due, in part, to thedifference in specific gravity. Practicing with a projectile withdifferent ballistics may contradict the advantages gained by practicing.It is well known in the art that the adjustments of the sights on afirearm are very dependent on the weight of the projectile. This hascaused a dilemma for hunting enthusiast. Presently this dilemma is notresolvable.

[0005] Shooting enthusiast, who primarily shoot at targets, havedifferent needs. The number of shots fired at a designated shootingrange can be very high. With lead projectiles there are severalalternatives none of which are suitable. The lead projectile can becaptured, in a sand pit, for example. Any material used to capture thelead is considered a toxic material and must be treated accordingly.This is cost prohibitive in many situations.

[0006] Many attempts have been made to create a projectile withacceptable properties yet which are free of lead. One approach, whichhas met with limited success, is the use of a binder within whichmetals, or metal alloys, are encased. The advantages of compositeprojectiles include the propensity to disintegrate on impact. Thiseliminates the need to capture the projectile. These types ofprojectiles are specifically for target shooting wherein maximumtransfer of kinetic energy is not a desire and, in fact, is preferablyavoided. The composite projectiles typically have a low specificgravity. The low specific gravity creates problems with flightconsistency and, in some cases, they have insufficient recoil toinitiate activation of the semi-automatic mechanisms of many firearms.While the composite projectiles are relatively successful for theshooting enthusiast the hunting enthusiast is still in a quandary. Thelow specific gravity renders these composites virtually useless forsimulating the trajectory of lead projectiles. Furthermore, the size ofthe projectile utilized for hunting is typically larger than that usedfor target shooting and the presently available composites are notsuitable for larger size projectiles.

[0007] In composite projectiles the binder acts as a matrix within whichthe metal, or metal alloy, is encased. The metal, or metal alloy, actsto ballast the projectile by increasing the specific gravity. Theballast is typically chosen from copper, tungsten, tungsten carbide,ferrotungsten, ceramic, bismuth, stainless steel, bronze and mixtures ofthese components.

[0008] Belanger, in U.S. Pat. No. 5,237,930, has described a compositeprojectile, comprising copper and nylon. The composition is demonstratedto achieve a projectile with a specific gravity of up to approximately8.3. This is an insufficient replacement for a lead projectile with aspecific gravity of approximately 11.3.

[0009] West et al., in U.S. Pat. No. 5,616,642, has describedimprovements to the projectile of Belanger. The projectile of West etal. utilizes a polyester resin with a higher specific gravity thannylon. These projectiles, while offering advantages, require jacketingto achieve the full advantages. The additional processing step is costprohibitive.

[0010] There has been an ongoing need in the art for a frangibleprojectile with characteristics similar to a lead projectile.

BRIEF SUMMARY OF THE INVENTION

[0011] Hence, it is object of the present invention to provide acomposite projectile with a specific gravity similar to lead.

[0012] Another object of the present invention is to provide a compositeprojectile with ballistics, which are predominantly dictated by specificgravity, similar to the ballistics for a lead projectile of the samesize and shape.

[0013] Another object of the present invention is to provide a compositeprojectile capable of fragmenting upon impact. A particular feature ofthe present invention is the ability to fragment with minimal ricochet.

[0014] A specific advantage of the present invention is provided in acomposite projectile substantially free of lead or alloys of lead.

[0015] Yet another specific advantage of the present invention isprovided in the ability to include lubricants and reinforcement fiber inthe binder of the composite projectile.

[0016] These and other advantages, as will be realized, are provided ina projectile comprising a ballast encased in a binder wherein the bindercomprises polyether block amide resin.

[0017] Another preferred embodiment is provided in a frangibleprojectile comprising a binder. The binder comprises about 10-30%, byweight, poly ether block amid resin. The ballast comprises tungsten.

[0018] Yet another preferred embodiment is provided in a frangibleprojectile comprising 34-94%, by weight, binder and 6-66%, by weight,ballast. The binder comprises poly ether block amide resin. The ballastcomprises at least one member selected from a group consisting oftungsten, tungsten carbide, molybdenum, tantalum, ferro-tungsten,copper, bismuth, iron, steel, brass, aluminium bronze, beryllium copper,tin, aluminium, titanium, zinc, nickel silver alloy, cupronickel andnickel. The projectile has a specific gravity of about 5 to about 14.

DETAILED DESCRIPTION OF THE INVENTION

[0019] The inventors of the present application have found, throughdiligent research, that frangible projectiles can be prepared with aballast, particularly tungsten, and a binder comprising alloys ofpolyether block amides.

[0020] The projectile of the present invention comprises ballast encasedin a binder. A particular advantage of the present invention is theability to incorporate high levels of ballast. Particularly, theprojectile comprises at least 6%, by weight, ballast, to no more thanabout 66% by weight, ballast. Below about 6%, by weight, ballast thespecific gravity of the projectile is unacceptably low resulting in poorballistic performance. More preferably the ballast is present in anamount of at least about 26%, by weight, to insure adequate consistencyof the ballistic characteristics. More preferably, the ballast ispresent in an amount of at least about 39%, by weight, at which pointthe specific gravity approaches the specific gravity of lead and theballistic characteristics of the projectile are predictive of theballistic characteristics for lead projectiles. Above a ballast level ofapproximately 66%, by weight, the projectile has an insufficient amountof binder to form a matrix sufficient to withstand the combined effectsassociated with the initial acceleration and heat generated duringfiring and the centrifugal force and air resistance which are realizedduring flight. More preferably the projectile has no more thanapproximately 49%, by weight, binder. Most preferably, the projectilecomprises approximately 45-49%, by weight ballast and 51-55%, by weight,binder.

[0021] The ballast preferably comprises a metal. Most preferably theballast excludes lead metal. Preferred ballast comprise at least onematerial selected from the group of tungsten, tungsten carbide(carballoy), molybdenum, tantalum, ferro-tungsten, copper, bismuth,iron, steel, brass, aluminium bronze, beryllium copper, tin, aluminium,titanium, zinc, nickel silver alloy, cupronickel and nickel.Particularly preferred ballast comprise at least one material selectedfrom the group of tungsten, tungsten carbide, molybdenum, tantalum,ferro-tungsten, copper, bismuth and iron. More preferred is a ballastcomprising at least one material selected from the group of tungsten,tungsten carbide, tantalum, molybdenum and ferro-tungsten. The mostpreferred ballast comprises tungsten. Particularly preferred is aballast consisting essentially of tungsten. For the present invention itis understood that the metals may be in the form of oxides, pure metals,or combinations.

[0022] The ballast is preferably incorporated as a powder. As would bereadily understood from the description herein, a powder more readilydisperses upon impact and imparts minimal kinetic energy to the target.The lower size limit of the ballast particles is chosen based onmanufacturing convenience. If the particle size of the ballast is tosmall the powder becomes easily distributed by airflow and becomes adusting hazard in the manufacturing process. This is undesirable in somecircumstances. An average particle size just large enough to haveminimal dusting is most preferred in most circumstances. The ability ofthe binder to wet the surface of the ballast is also a consideration inchoosing particle size. If the surface of the ballast is not properlywetted by the binder a larger particle size may be required to insureadequate specific gravity and to exclude air inclusion. The upper sizelimit is dictated by the acceptable amount of energy the target canwithstand. It is most preferred that the particle size be at least about149 to no more than about 1,000 μm.

[0023] The binder comprises poly ether block amide resin (PEBA). PEBA isa regular linear chain of rigid polyamide segments interspaced withflexible poly ether segments. PEBA is readily available commerciallyunder the trade name PEBAX®. The binder may comprise additionaladditives which are advantageous to the composite projectile.Particularly preferred are additional resins blended, or alloyed, withPEBA. Additives can be employed to assist in the manufacturing processsuch as wetting agents. It has been found to be particularlyadvantageous to incorporate lubricants and/or reinforcing fibers intothe binder.

[0024] PEBA is a copolymer of amides and ether. A particularly preferredembodiment is a high specific gravity PEBA. PEBA can be alloyed withother resins such as nylon and polybutylene terephthalate (PBT).Particularly preferred nylon resins include nylon 6, nylon 6/6, nylon 11and nylon 12. In a particularly preferred embodiment PEBA is alloyedwith high specific gravity nylon. Blends of PEBA with nylon arecommercially available from various sources. In a preferred embodimentthe binder comprises at least approximately 10%, by weight, PEBA to nomore than about 30%, by weight, PEBA. The remainder of the bindercomprises a second resin, and other materials such as lubricants andfibers. In a particularly preferred embodiment the binder comprises atleast about 70%, by weight, to no more than about 90%, by weight, secondresin selected from nylon and PBT.

[0025] It is preferred to incorporate lubricants into the binder tofacilitate manufacturing, reduce wear rate and increase pressurevelocity limits. It is most preferred that the lubricant be blended intothe binder. The lubricant can be solid or liquid with a solid beingpreferred. Migrating lubricants are particularly preferred since theycan be incorporated at lower levels in the matrix. Particularlypreferred lubricants include molybdenum disulfide, silicone,polytetrafluoethylene (PTFE) and mineral oil.

[0026] Molybdenum disulfide is a particularly useful solid lubricantwhen incorporated into the inventive binder. While not limited to anytheory, molybdenum disulfide is considered particularly useful forreducing wear rates and increasing pressure velocity limits. Molybdenumdisulfide is also considered to be a nucleating agent and mayparticipate in enabling the molded part to have a very fine crystallinestructure.

[0027] Silicone is a particularly advantageous boundary lubricant.Silicone reduces wear rates and coefficients of friction when compoundedat lower levels into the inventive binder. Silicone migrates to thesurface of a molded part due, in part, to the limited compatibility withthe binder. The migrating silicone provides a near continuous generationof silicone film which serves as a boundary or mixed film lubricant.

[0028] PTFE, when compounded with the binder of the present invention,significantly reduces the wear rate of a composite. PTFE has a very lowcoefficient of friction. A particularly preferred lubricant is a mixtureof PTFE, silicone and mineral oil. The mixture provides immediatelubrication from the migratory silicone which acts to enhance wearcharacteristics at high speeds or velocities and increases pressurevelocity compared to lubrication alone.

[0029] Fibers have been demonstrated to be particularly beneficial whenincorporated into the binder. Fibers which are advantageously added tothe binder include nylon fibers, glass fibers and carbon fibers. Nylonfibers are particularly preferred. A particularly preferred nylon fiberis aramid. In a particularly preferred embodiment aramid fiber is addedat levels of about 1 to about 30%, by weight, to the binder. Morepreferably the fiber is added at levels of about 1 to about 15%, byweight. Even more preferably, the fiber is added at levels of about 3 toabout 7%, by weight. Particularly preferred is about 5%, by weightfiber. Incorporating aramid fibers increases the lubricity of the binderand reduces the wear factor of the thermoplastic resin of the binder. Aparticularly preferred embodiment incorporates aramid fibers inconjunction with silicone and PTFE. This combination further reduceswear rates and frictional coefficients.

[0030] Aramid fibers are nylon comprising an aromatic ring in the nylonbackbone. Particularly preferred aramid fibers include Nomex®, Kevlar®,and blends thereof.

[0031] The specific gravity of the composite projectile is preferablyapproximately equal to the specific gravity of lead for reasons setforth herein. Even though this is most preferred it is also understoodthat the advantages offered with the composite projectile can beadvantageous at other levels of specific gravity for differentapplications. For example, it is not uncommon for shooting enthusiast toutilize sub-optimal materials, such as copper projectiles, due to theenvironmental concerns associated with lead. One advantage of thepresent invention is the ability to utilize the composite projectile atlower specific gravity levels to accommodate various applications in theart. A shooting enthusiast may, for example, typically utilize aprojectile with a specific gravity of 8. While this is known to be lessthan desirable the environmental hazards associated with lead dictate,in some cases, use of a projectile that is less than desirable. Thepresent invention can be utilized at a lower specific gravity toaccommodate the shooting enthusiast thereby allowing them to takeadvantage of the superior properties of the inventive projectile withoutadjusting the sights of the firearm. A particular advantage of thepresent invention is the ability to provide a superior projectile at aspecific gravity of lead and at specific gravity levels commonlyemployed without foregoing the other advantages, such as low ricochet,offered by the inventive projectile. It is preferred that the compositeprojectile have a specific gravity of at least 5, more preferably atleast 5.7, to insure adequate recoil for use in semi-automatic firearms.More preferably the specific gravity is at least 8 to insure adequateflight consistency, which leads to improved accuracy. Even morepreferably the specific gravity is at least 10. Most preferably thespecific gravity is at least 11. A specific gravity above the specificgravity of lead is achievable but not desirable in most circumstances.It is most preferred that the specific gravity not exceed approximately14. It is most preferred that the specific gravity be at least about 11to no more than about 11.5.

[0032] The projectile of the present invention exhibits excellentresults with regard to the low amount of fragmented material ricochetingfrom the target. Reduced Ricochet is a function of the degree ofdensification and the type of consolidation technique, such as injectionmolding under pressure. Powder particle size and porosity. The higherthe specific gravity or density, the greater the degree of reducedricochet.

[0033] The projectiles of the present invention can be preparedutilizing standard molding techniques. It is preferable to maintainlower melt temperatures of less than 490-520° F. with the inventivecomposites to avoid separation of the filler and resin which can occurat excessively high temperatures. A melt temperature of approximately500° F. is eminently suitable for demonstration of the teachings herein.

EXAMPLES Example 1

[0034] Projectiles of the present invention were prepared in accordancewith the following procedure. A composition was prepared comprising 90%,by weight, tungsten and 10%, by weight PEBA alloyed with impact modifiednylon 6 which was internally lubricated with Silicon, PTFE and MineralOil. Tungsten metal was obtained from Micron Metals, Inc. as WP106. PEBAwas obtained from Atofina Chemicals, Inc., as PEBAX. Impact modifiednylon 6 was obtained from LNP Engineering Plastics, Inc. as ThermocompHSG-P-1100A EXP. The mixture was dried for a minimum of 4-6 hours at180° F. in a dehumidifying oven prior to molding into a projectile. Aconventional ram, or reciprocating screw injection molding machine wasused to form the projectile. The processing conditions included a moldtemperature of 180° F., and a melt temperature of 490° F. at 25,000 psi.A 9 mm projectile was prepared with a weight of 124 grains and a lengthof 0.600 inches. The specific gravity was measured, using standardtechniques, to be 11.2. The cited art is incapable of preparing a stableprojectile with the weight and density obtained with the sampleprojectile. The 124 grain 9 mm projectile was loaded and fired from a 9mm cal Beretta 92 SM 4.3 inch barrel pistol producing an averagevelocity of 1109 feet per second and a chamber pressure of 28,520 PSI ata distance of 7 yards against a ¼ inch AISI steel plate 48×48×¼ at astriking angle of 10 degrees. The Reduced Ricochet Limited Penetration 9mm projectile completely disintegrated producing no “Splashback” orprojectile fragments.

Example 2

[0035] A projectile was prepared in accordance with the procedure andcomposition described in Example 1. A 5.56 mm projectile was prepared ata weight of 62 grains and 0.740 inches in length.

Example 3

[0036] A projectile was prepared in accordance with the procedure andcomposition described in Example 2. A subsonic 5.56 mm projectile wasprepared at a weight of 114 grains and 1.15 inches in length.

[0037] The present invention has been described with particularreference to the preferred embodiments. These embodiments are intendedto provide teachings that would allow one of ordinary skill in the artto utilize the teachings herein without undue experimentation. Theinvention is more clearly set forth in the claims which are appendedhereto.

Claimed is:
 1. A projectile comprising a ballast encased in a binderwherein said binder comprises polyether block amide resin.
 2. Theprojectile of claim 1 comprising about 6 to about 66%, by weight, saidballast and about 34-94%, by weight, said binder.
 3. The projectile ofclaim 2 comprising x-x %, by weight, said ballast and y-y %, by weight,said binder.
 4. The projectile of claim 1 wherein said binder furthercomprises a second resin.
 5. The projectile of claim 4 wherein saidbinder comprises about 10 to about 30%, by weight, said polyether blockamide resin and about 70 to about 90%, by weight, said second resin. 6.The projectile of claim 4 wherein said second resin is selected from agroup consisting of nylon and polybutylene terephthalate.
 7. Theprojectile of claim 1 wherein said ballast comprises at least one memberselected from a group consisting of tungsten, tungsten carbide,molybdenum, tantalum, ferro-tungsten, copper, bismuth, iron, steel,brass, aluminium bronze, beryllium copper, tin, aluminium, titanium,zinc, nickel silver alloy, cupronickel and nickel.
 8. The projectile ofclaim 7 wherein said ballast comprises at least one member selected froma group consisting of tungsten, tungsten carbide, tantalum, molybdenumand ferro-tungsten.
 9. The projectile of claim 8 wherein said ballastconsist essentially of tungsten.
 10. The projectile of claim 1 whereinsaid projectile has a minimum specific gravity of
 5. 11. The projectileof claim 10 wherein said projectile has a minimum specific gravity of10.
 12. The projectile of claim 1 wherein said binder further comprisesa fiber.
 13. The projectile of claim 1 wherein said binder furthercomprises a lubricant.
 14. A frangible projectile comprising: a bindercomprising about 10-30%, by weight, poly ether block amid resin; aballast comprising tungsten.
 15. A frangible projectile comprising:34-94%, by weight, binder wherein said binder comprises poly ether blockamide resin; and 6-66%, by weight, ballast wherein said ballastcomprises at least one member selected from a group consisting oftungsten, tungsten carbide, molybdenum, tantalum, ferro-tungsten,copper, bismuth, iron, steel, brass, aluminium bronze, beryllium copper,tin, aluminium, titanium, zinc, nickel silver alloy, cupronickel andnickel; and wherein said projectile has a specific gravity of about 5 toabout
 14. 16. The frangible projectile of claim 15 wherein saidprojectile has a specific gravity of at least about
 10. 17. Thefrangible projectile of claim 16 wherein said projectile has a specificgravity of about 11 to about 11.5.
 18. The frangible projectile of claim15 wherein said ballast consist essentially of tungsten.
 19. Thefrangible projectile of claim 15 further comprising a second resin. 20.The frangible projectile of claim 19 wherein said second resin isselected from a group consisting of nylon and polybutyleneterephthalate.
 21. The frangible projectile of claim 19 wherein saidsecond resin is nylon selected from a group consisting of nylon 6, nylon6/6, nylon 11 and nylon
 12. 22. The frangible projectile of claim 15wherein said binder further comprises a fiber.
 23. The frangibleprojectile of claim 22 wherein said fiber is an aramid.
 24. Thefrangible projectile of claim 15 wherein said binder further comprises alubricant.
 25. The frangible projectile of claim 24 wherein saidlubricant is at least one material chosen from a group consisting ofmolybdenum disulfide, silicone, polytetrafluoethylene and mineral oil.